To force heated air into certain rooms, or to save a little energy, some homeowners may close the heat vents in rooms that go unused in the winter. Nest Thermostat Generation 3 2 years ago. I came home from work and the house was 80 degrees. This can cause the air to feel only lukewarm. In such a case, there could be an easy solution, particularly if your thermostat setting is the problem. If you’re wondering why your heater is blowing out cool air, the first thing you should do is check your thermostat and make sure it’s set to the correct temperature. 1. share. The air coming from your supply vent should be anywhere from 15-30 degrees hotter than the air near your return vent (depending on how cold it is outside). Frost on the outside coil is condensation that forms up on the coil in the form of frost. Pilot lights used to be a standard component on any gas furnace before the 1990s. If you can see the burner in your furnace, you may be able to visually inspect the flame sensor for cracks in its porcelain base, or soot build up on its tip. Families with young children know that heat registers can often get closed mysteriously after a play session. Major duct problems. You want to curl up in a cozy house after you deal with harsh weather conditions, so it’s time to take a look at the reasons the furnace may be blowing cold. Incorrect thermostat settings... a wave of cool air from your heat vent before the warm air arrives... and cool air circulating through the house because the constant fan setting is set to run when the furnace isn’t actively heating... these are all common reasons for a heating system blowing cold air. Less commonly, if you have a duel-fuel system (heat pump/gas furnace combination) the heat pump will warm your home with a lower air temperature than provided by the gas furnace, which could make it seem like your system is blowing cold. If the pilot light won’t stay lit, it’s possible that there is an issue with the thermocouple or ignition system. Many modern furnaces have a computer control board with coded LED lights that flash to provide you with information on problems with your furnace. On my way to the destination, which was the whole 3 hours, the heater was blowing heat like normal. Have an expert inspect your ducts along with the furnace. Blocking air increases the air pressure in your air ducts, which may both cause and worsens airflow leaks—particularly at joints and seams. A dirty flame sensor may cause your furnace to function improperly. Inadequate gas supply. There are two possible routes here, one of which many homeowners who are new to heat pump systems encounter. To troubleshoot a misbehaving gas furnace, start with the easiest explanations and solutions, then work your way to the most complicated. Maybe the fan is malfunctioning. 2013 explorer, is there a separate - Answered by a verified Ford Mechanic A properly working flame sensor will shut down the furnace if it does not detect a flame while the gas valve is operating. Check fuses and the circuit breaker to ensure that power is getting to the furnace. Tried to bleed air from coolant/ heater core lines, but … Scrub the sensor gently to remove dust and other residues. Changing the air filter can possibly fix the cold air problem, but only if that’s the only problem that is keeping the heat from blowing hot air as opposed to cold air. If your car is blowing cold air that means that, the hot coolant is not reaching the heater core. If you notice a room is too cold or hot... inconsistent temperatures in different areas of your home... the temperature reading on your thermostat doesn’t match the temperature you set... or if your furnace is constantly turning on and then back off after a short time (short cycling), you may have too many closed vents. The air coming from your supply vent should be anywhere from 15-30 degrees hotter than the air near your return vent (depending on how cold it is outside). It continues to blow when it's in auxiliary also but w/o heat just air. Ensure that there is actually a problem when your heat pump is blowing cold air. If it does, and you still want to close a few vents, try closing fewer vents this time. This helps to prevent natural gas (or propane) from continuing to flow into the home’s air supply. There is a good chance that you will find and correct the reason why your furnace is failing to produce warm air. Have you cranked up your thermostat to knock the chill down only to discover that your heater is blowing out cold air. It’s also the reason that a plugged heater core, stuck thermostat, or air in the cooling system can all cause a car’s heater to blow cold. Changing the fan setting to auto will turn off the blower when the system is not actively heating. level 2. Try opening all of your heat vents and see if that solves the problem. Until the engine warms up, there’s no heat for the heater core to extract. There could even be a puddle of liquid under the front of the vehicle. Neither your air conditioning nor your heater will be cold or hot right after you turn them on. Why a Heat Pump Will Blow Cold Air. Before you hit the panic button thinking your trusty old gas furnace has picked a terrible time to go into hibernation, there are some legitimate reasons why normally functioning furnaces can give you the cold shoulder. This is different from a furnace, which can blast hot air over 100°F. In other words, it's not putting out any heat at all. I am just wondering if I hooked something wrong hooking up the thermostat , or perhaps I have a problem with the heat pump and need to call someone out to fix the problem. Learn about our energy efficient innovations that can help you save on your heating & cooling energy expenses, while ensuring your home is comfortable. And, if your furnace does have a pilot light ignition, it may be time to consider upgrading to a new, pilotless gas furnace. A new furnace can offer higher energy efficiency, new product reliability and warranties, and no issues with pilot lights blowing out. There are a few reasons your heat pump could be blowing cold air. A lack of heat can be a symptom of a much larger problem. The coolant supply is blocked. Basic filters are often inside the furnace cabinet, but larger, 4-inch media filters, electronic air cleaners, and whole-home air purifiers are likely mounted outside the furnace between the cabinet and the return air duct. It use to work months ago on every setting but always made a really loud noise when on until it only worked on high still make a kinda loud sound. Air in the cooling system impedes the circulation of coolant in the system, and as a result, the heater blows hot air only when driving, and cold air at idle. 1.Your Heater hasn’t had time to warm up. The sound you hear is the reversing valve switching your unit over to cooling mode. After verifying that the thermostat is set properly and is getting power, ensure that the furnace itself is getting power. Posted on Nov 13, 2008 If the furnace powers up, you should soon have heated air cycling through your home once again. It could even be running in the air conditioning mode due to a malfunction. You may also see an error message on your thermostat, or a blinking LED light on the furnace control board. If your heater starts by throwing warm air out of your registers, but you are soon left with a heater blowing cold air, then I would suspect that your flame sensor needs to be cleaned. Here’s the downside of a heat pump: The warmth of the air it produces is entirely dependent upon the outside temperature. Report Save. There are many reasons your car's heater isn't working. The upper radiator hose is hot and the lower radiator hose is cold. The furnace blowing cold air, or there is no heat in the house. 9 out of 10 times, when the heater is not heating the air, it is a bad heater core. Maybe your heater is not blowing hot air even though the fan is running. The flame sensor safeguards your furnace by ensuring that gas flows only when there is a flame to ignite it. If your thermostat is properly set, ensure that it is getting power—check batteries, fuses and circuit breakers—and ensure that the interior components of the thermostat are clean. If it’s dirty, change it! When overheating, your furnace can trip a high limit switch, causing the furnace burners to shut off so that the heat exchanger does not crack. The nest seems to blow warm air normally but once it switches to alternative heat source, then it starts blowing cold air. It started overheating and the heater blows cold air. Many of these are particular to more sophisticated high-efficiency condensing furnaces that use electronic ignition, and most homeowners prefer to call a service technician to deal with them. Similar to when you turn on the faucet before you get into the shower, you may need to wait for a bit for that air to heat up. However the heat registers were closed, if too many are shut, it can cause heat to build up in your furnace, causing it to shut down automatically. If your car heater is suddenly blowing out cold air instead of heat in the middle of a bitterly cold winter, you have a good reason to be frustrated. If your heater is blowing cold air, and it’s not one of the first two possible explanations on this list, then you’ll need a specialist to at least come and take a look. If you’re unable to warm your home with your furnace, and you’re looking for Heating And Air Companies in Atlanta, Moncrief Heating & Air Conditioning can help. Since the 1990s, the industry has shifted to using pilotless ignition systems such as hot surface igniters, so pilot-related issues are becoming less common. Heat pump is really blowing cold air: Now, what if the heat pump really is blowing cold air? Temp gauge looks normal, and heat blows when car is moving. Tim H., HVAC Professional. With a dirty flame sensor, your gas burner won’t stay lit, causing the air to go cold soon after the furnace turns on. 8 Common Problems With Conventional Gas Furnaces, Troubleshooting an Electronic Ignition Furnace That Won't Light, Troubleshooting an Intermittent Pilot Ignition System, How to Light the Standing Pilot Light on a Gas Furnace, How to Troubleshoot Electric Ignition Furnace Problems, How to Replace a Furnace Thermocouple or Electronic Flame Sensor, How to Check a Pilot Light on a Gas Furnace, Troubleshooting Common Problems With a Gas-Fired Hot Water Boiler. In some cases, a malfunctioning thermostat may require adjustment or replacement. Most cooling systems have a bend door that controls the flow of the air through the heater core. Automotive Mechanic. If the heater is blowing cold air and the car is overheating, it is likely that the problem is related to the engine cooling system as well. However, furnaces are “sized” to efficiently deliver comfort to the entire home. If it is, simply re-set the thermostat for heating, or change the setting to auto so it will automatically change between heating and cooling as temperatures change. Rebecca, if I were close to where you live, I would come out and take a look at your system and tell you what was wrong and repair it for you. If the pilot light is out, follow the manufacturer’s directions on how to relight the pilot. It will make all our explanations make way more sense. Possible Conclusion 1: It’s Not Blowing Cold Air Heat coming out on driver side only, cold air blowing out on passenger side. Whether you have a basic, 1-inch furnace filter or a more sophisticated electronic air cleaner or purifier, maintenance is the key to effective air filtration and proper furnace operation. Compromised flame sensor. 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